1. Field of the Invention
This invention pertains generally to electrical distribution panels and, more particularly, to electrical distribution panels accommodating non-critical loads and critical loads being supplied with power from a backup power source in response to power from a primary power source becoming unacceptable.
2. Background Information
Electrical distribution panels, such as load centers, incorporate a plurality of circuit breakers and provide a safe and controllable distribution of electric power. Such load centers have become a common feature in both residential and commercial structures.
A known proposal for either new construction or the retrofit of existing installations involves the addition of a separate load center panel for critical circuits. This separate load center panel receives a backup power source and, also, manually switches between a utility power source and the backup power source. This can be utilized in installations that incorporate the backup power source, such as an electric generator, in the event that the utility power source becomes unacceptable (e.g., without limitation, fails; becomes unreliable; becomes unavailable). This can provide, for instance, reliable electric power for doctor's offices away from hospitals, home-based businesses and home-based chronic patient care support. For existing installations, this requires that the critical circuits be moved (e.g., rewired) from a first load center to the separate load center panel.
One known system employs a single interlock between the main circuit breaker and a manual transfer switch. In response to loss of utility power, the user must first manually turn off any non-critical circuits, turn off the main circuit breaker, and then turn on the transfer switch. The manual sequence is reversed when utility power has returned.
Today, it requires significant time and effort to rewire a load center in order to connect a backup power source, such as an electric generator or other auxiliary power unit (APU) (e.g., a device whose purpose is to provide electrical energy), to critical circuits in, for example, residential and relatively smaller scale commercial structures.
There is also an increased demand for reliable power to homes, particularly in regions with bad weather seasons. Furthermore, there are an increasing number of elderly persons who want to maintain their independent lifestyle and receive healthcare in the home. Hence, in these applications, it is important to provide automatic backup generation and optional surge protection for critical loads including, for example, heating, ventilation and air conditioning (HVAC), medical equipment, refrigeration, and other daily needs.
There is room for improvement in electrical distribution panels.